The present invention relates to communications systems and more particularly to power line communications systems. Electric power companies typically have a service person visit customers and read a power meter to determine the amount of power consumed for billing purposes. This can become very cumbersome and time consuming with a large number of customers.
It would be beneficial for power companies to read electric power meters remotely. Power lines are wires that convey power signals from a power source, such as a power generation station to a power customer, such as a home or business. There are extant power lines to each customer's power meter and these are advantageously configured for communicating data between a power company and power meters. However, conventional modulation techniques are not readily adaptable to operate in the high-power, high-noise environment of a power line.
Conventional solutions to the problem of transmitting data over a power line typically utilize complex and cumbersome equipment and techniques in order to perform reliably in the high-power, high-noise, phase distorted power line channels. For example, some systems monitor different frequency channels, select an appropriate channel, and then indicate the appropriate frequency to other communicating units. Others employ a plurality of signals which are not harmonically related. This requires complicated filtering and signal extraction.
Currently there is a need for a less complicated communication system that employs existing power lines to efficiently transmit data.